If you’re having trouble sleeping, melatonin is a popular and easy remedy. It’s effective for many people, doesn’t have any serious safety issues, and is available as pills or gummies for pennies a dose. It’s also misunderstood, though: melatonin is not a traditional sleeping pill.

Our actions throughout the day, like when we go to sleep and when we eat, are partly programmed by a system of brain signals and hormones that make up our body’s clock. Melatonin helps to keep the body clock synced with the earth’s cycles of night and day through the convenient sunlight detectors in the front of your face. You know, your eyeballs.

Some of the light that enters our eyes helps to signal a part of the brain called the suprachiasmatic nucleus (SCN). At nighttime, little to no light comes in, and the SCN tells the nearby pineal gland to make melatonin, which then circulates through our blood.

Melatonin supplements add to the amount of melatonin circulating in our blood. Even small doses from pills, around 0.5 milligrams, can boost the amount circulating in our body. Most melatonin pills are between 0.5 and 5 milligrams. Higher amounts aren’t necessary; the signal doesn’t seem to depend on dose. (Imagine shouting to someone that it’s nighttime, versus telling them in a quiet voice. They’ll get the message either way.)

This effect may be partly responsible for some of the confusion over how well melatonin works. Vox recently reported on several reviews of melatonin studies. One doctor described melatonin’s effect on insomnia as positive but weak; another said melatonin is “a lousy sleeping pill.”

These different studies may be hiding a real effect that only applies to people with certain body clock issues. Dr. Nitun Verma, a Stanford-trained sleep specialist and longtime friend of Lifehacker, says that “it’s difficult to say what percent of people will benefit from melatonin because some research studies look at a population who only have insomnia, or delayed sleep phase syndrome (DSPS), or a combination.”

Delayed sleep phase syndrome is common in young adults and people in the tech industry, Dr. Verma says, and people with DSPS are more likely to benefit from melatonin than people who just have insomnia.

Should You Take Melatonin?

Even if your problem is one that melatonin can help with, melatonin isn’t the only answer. Exposing your eyeballs to sunlight and darkness at appropriate times also helps to sync up your hormones and retrain your brain. That’s why screens at bedtime can screw up your body clock: your brain gets the “daytime” signal when it’s really night. On the flip side, it’s not smart to take melatonin and then watch movies on your iPad while you wait to fall asleep.

Don’t forget to consider other reasons why you might be having trouble sleeping. Do you have a sensible sleep schedule and a bedtime routine that gets you in the mood to sleep? Make sure to cover those bases, too.

Insomnia can also be a symptom of other medical or mental problems, including depression, anxiety, and sleep apnea. If insomnia is interfering with your life, and especially if you have other medical or mental issues that could be related, talk to a professional. Your regular doctor is a good place to start, or you can find a local sleep specialist with this directory from the National Sleep Foundation. They can help figure out if there’s an underlying cause for your insomnia, and they may be able to recommend more comprehensive support.

Every drug has its risks, and thankfully melatonin doesn’t have very serious ones—at least as far as our current studies have shown. An Australian pediatrician warned last year that we shouldn’t assume melatonin is safe for children, since its long term effects haven’t been studied very well. One concern is that long-term use might affect the hormones involved in puberty. Melatonin has effects throughout the body, and Dr. Verma points out that it may also interfere with fertility, so he doesn’t recommend it for people who are trying to conceive.

Melatonin can also interfere with how your body processes other drugs, including birth control. As always, it’s wisest to discuss your situation with your doctor.

If you’d like to try melatonin, you can buy it as a dietary supplement in the United States and Canada. It’s considered a prescription drug in many other places, including much of Europe. Because it’s a supplement, our Food and Drug Administration doesn’t keep a close eye on how the pills are produced. Supplements are always a bit of a gamble, so keep that in mind.

“More like a warm glass of milk than being knocked out with a blunt object,” was a typical description.

I asked a few people who use melatonin regularly how they would describe the feeling. All agreed that its effect is more gentle than something like Benadryl, the infamously drowsy-making allergy medicine.“More like a warm glass of milk than being knocked out with a blunt object,” was a typical description. All agreed that it didn’t make them sleepy in the morning, either. One complaint I heard a few times was that it gave people extremely vivid dreams. It’s not clear if crazy dreams are a side effect of melatonin, or just something that happens when you catch up on sleep.

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So melatonin is a real drug that may help you sleep—depending on exactly why you’re not sleeping. Don’t expect miracles, and do make sure to take it at the right time: ideally five hours before your intended bedtime. Because we don’t know a whole lot about potential risks, most sources I consulted for this article say to use the lowest dose that works (try 0.5 milligrams to start) and if you intend to use it long term, talk to your doctor.